Subtraction lung image for evaluating pulmonary ventilation in xenon-enhanced CT

Area of Science:

• Medical Imaging
• Pulmonary Physiology
• Radiology

Background:

• Xenon-enhanced CT (Xe-CT) is used for lung imaging.
• Accurate assessment of pulmonary ventilation is crucial for diagnosing lung diseases.
• Current Xe-CT protocols can involve significant radiation exposure.

Purpose of the Study:

• To develop a method for transforming Xe-CT images to improve overlap with baseline images.
• To create subtraction images for evaluating pulmonary ventilation.
• To demonstrate the clinical utility of this new Xe-CT technique.

Main Methods:

• Eight healthy men underwent Xe-CT lung studies with different inhalation/exhalation protocols.
• Helical CT scans were acquired during xenon washin and washout phases.
• Two-dimensional geometrical warping using polynomial functions was applied to align images.

Main Results:

• Subtraction images during xenon washin directly reflect pulmonary ventilation.
• Geometrical warping increased the evaluable area in subtraction images by 0.3%-22.0%.
• Ratios of specific ventilation from subtraction images to ventilation maps were high (0.88-0.96).

Conclusions:

• Subtraction lung images during washin provide quantitative pulmonary ventilation data.
• This method requires only two scans, reducing radiation exposure.
• The proposed Xe-CT subtraction method with geometrical warping is clinically applicable for ventilation assessment.